1. Field of the Invention
This invention relates generally to stator frame fabrication, and, more particularly, to a stator frame useful in alternating current traction motors for locomotive applications.
2. Description of the Related Art
One conventional method of stator frame fabrication uses an octagonal stator lamination punching with two cast end pieces and four cast tie bars. Stator laminations are clamped between the end pieces which are joined by the tie bars. The end pieces and tie bars require machining prior to assembly including extensive milling of flat surfaces for attachment. Additionally, a large number of individual welds are used, including, for example, filet-type, "J" groove, and butt welds. Because the welding requirements vary from corner-to-corner, the resulting lack of symmetry requires that special biasing techniques be used during fabrication to compensate for unequal weld shrinkage during frame assembly to insure sufficient accuracy of the finished stator lamination bore.
Another conventional method of stator frame fabrication uses a circular lamination punching with two circular-shaped cast end pieces and four arched tie bars. In addition to requiring two heavy butt welds for each tie bar, this method may require difficult machining procedures to prepare the arched bars for attachment.